NetSafe and Microsoft are warning that phone scammers are targetting people offering to fix viruses on their computers and defrauding them of money.
Both organisations have reported a significant increase in reports of scammers claiming to be calling from Microsoft about a problem with their computers.
The cold callers offer to fix compromised computers and ask for remote access to them in the hope of getting credit card details or bank account numbers.
People have allowed access and one person is reported to have lost about $5,000.
Microsoft New Zealand said the company would never call people asking for remote access to their computer.